Dispensing device



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ATTORNEY E. c. WEISKOPF DISPENSING DEVICE Filed. Jan. 25, 1932 Feb. 13,1934.

1934- E. c. WEISKOPF DISPENSING DEVICE Filed Jan. 25, 1932 3Sheets-Sheet 2 INVENTOR. $4 M. (1

BY 7 ATTORNEY mm vlllidi 13, 1934- E. c. WEISKOPF DISPENSING DEVICEFiled Jan. 25, 1932 5 Sheets-Sheet 3 IN V EN TOR.

A TTORNEY AIM; C W- Patented Feb. 13, 1934 DISEENSENG DEVECE Edwin C.Weiskcpf, New York, N. Y.

Application January 2 5, 1932. Serial No. 588,743

19 Claims.

This invention relates to dispensing devices.

In making tests, as for example, in chemical or biological laboratories,it is often necessary to dispense small quantities of iquid at regularintervals for example, in the making of Wasserman tests.

This invention is directed to the provision of a simple, practical andeffici nt machine for automatically ace mplishing this purpose.

An object of invention is to provide a machine of the characterdescribed, for repeatedly dispensing small quantities liquid, havingmeans for adjusting the quantity of liquid dispensed, the constructionthe being such f rthermore, that the dispensed liquid may We. supply.

A further ob ect invention is to provide a motor operated practical and.gged por able a achine of the character described, whi

shall be inexpensive to manufacture, smooth, ac-

curate and positive in operation, easy to assemble, control and and yetefiicient to a high degree.

Other objects of tlie invention will in part be 1 obvious and in part.ereinafter pointed out.

The invention accord igly consists in the features of construction,combinations of elements, and arrangement or" parts which will beexemplilied in the construction hereinafter described, 3 of which "hescope of application will indicated in he following claims.

In the accompanying drawings, in which is shown of the various possibleillustrative embodiments of this invention,

Fig. l is a side elevational view of a machine embodying the inventionwith a side wall thereof removed;

Fig. 2 is a top plan view of the structure shown in Fig. 1;

r Fig. is a fragmentary cross-sectional View taken on lin 3-3 of Fig. 2;

Fig. 4 is a partial cross-sectional view taken on line 4-4 of Fig. 3;

. 9 is a vf w on a smaller e scale, similar to showing another positionof the parts;

(Q1. fil -103) Fig. 1G is a cross-sectional View taken on line 1010 ofFig. 3.

Referring now in detail to the drawings, 10 designates a machineembodying the invention here shown in the form of an automatic pipettedevice adapted to dispense small cuiantities of liquid at regularintervals. The machine 10 comprises a portable prismatic box 11 adaptedto rest on a table or like support. The box 11 comprises a bottom wall12 and a top wall 13 interconnected by pairs of posts 14 and i5, and 16and 17 respectively, located at the front and rear ends of the box. Afront wall 18 may be attached to the front posts 14 and 15, and a rearwall 19 may be attached to the front posts 16 and 17. The box mayfurthermore be provided with perfora-ted. side walls 22 and 23.

Mounted on the top wall 13 adjacent the front end of the box, is amember 25 having a flange portion 26 contacting the upper surface ofsaid top wall, and an upstanding tubular sleeve portion 27, open at theupper end thereof, and formed with a pair of aligned notches 28 and 29in the upper edge thereof. The member 25 may be attached to the top wall13 by means of screws 39, or in any other suitable manner. Removablymounted within said sleeve portion 27 is a valve housing 32 comprising acylindrical portion 33 having an inner tapered or conical surface 34,and formed with an outwardly extending horizontal short pipe or tube 35on one side thereof, having a passage 36 communicating with the interiorof the housin Said housing is further formed with a pair of alignedoutwardly extending pipes or tubes and 39 extending outwardly from theopposite side thereof, and with passages 38a and 39a, respectively,communicating with the interior of the housing. It will be noted thatthe tube 35 engages within the notch 29 of the tubular wall 27, and thelower tube 39 engages within the notch 28 of said tubular portion.whereby said Valve housing 32 is retained against rotary movement withrespect to the member 25. A thumb screw so fixed to valve portion 33 isadapted to engage a notch 40a formed in the upper edge of cylindricalwall 27 and a thumb screw 41 screwed to the outer end of said screw isadapted to press against the outer surface of said wall to releasablyretain said member 32 against removal from member 25, Obviously, uponloosening the thumb screw, the member 32 may be lifted from said tubularmember 27.

Rctatably mounted within the tubular member 33 is a tapered orfrusto-conical valve or cock 42 having a flange 43 contacting the bottomedge of said tubular portion 33. The upper end of said valve is formedwith an annular groove 42a, and a semi-circular member 422) pivoted tothe upper end of the housing portion 32 is adapted to engage within saidgroove to prevent axial movement between said valve member and housing.The valve 42 is preferably provided with a pair of transverse inclinedthrough passages 44 and 45 so arranged that in one angular position ofsaid valve, the passage 44 interconnects the passage 36 with the passage39a, and in another position of said valve, the passage 45 interconnectsthe passage 36 with the passage 38a. The flange 43 is provided with asegmental cut away portion or notch 46, and a pin 47 secured to thelower edge of the tubular portion 33 projects into said notch, saidnotch being so arranged that upon oscillating the valve 42, the limitsof oscillation of said valve will bring the passages 44 and 45,respectively, in communication with the passage 36. Attached to thetubular portions 38 and 39 are rubber tubes 56 and 51 respectively,serving respectively as outlet and inlet tube, as will appear more fullyhereinafter.

For the purpose hereinafter described, there is fixed to said top wall13 of the box 11, an elongated longitudinal guide member 54 having aninverted T-shaped slot 55 aligned with the tubular portion 35 of thevalve housing 32. Slidably mounted on said guide member is a member 56having a portion 57 extending within said slot, and a wall 58 extendingupwardly therefrom. Fixed to said portion 57 is a vertical upwardlyextending screw 59. A washer 66 having a central opening receiving theupper end of the screw is adapted to extend beyond the slot 55 so thatportions of the washer may contact the upper surface of the guide member54. A screw threaded member 61 screwed to the upper end of the screw 59is adapted to be turned by a handle 62 for pressing the washer againstthe upper surface of the guide member to fix the member 56 to said guidemember in various adjusted positions. Attached to the upper end of theupstanding wall 58 is a forwardly extending flaring or conical shapedmember 63 having a radial slot 64, the upper end of said wall 58 beingformed with a slot 65 registering with slot 64 and extending to thecenter of said conical shaped member.

Mounted on and between said member 56 and said tubular portion 35 is asyringe or similar pumping device 68, comprising a barrel 69 having atubular portion 70 preferably made of glass or the like transparentmaterial. Attached to the forward end of the tubular member 70 is ametal tip '71 having a forwardly projecting por tion '72 adapted to bereceived within a passage 35a of said tubular portion 35. At the rearend thereof, the tubular member 70 is provided with a metal collar 73adapted to be received within and contact the flaring portion 63 of themember 56. Slidably mounted within the glass tube '70 is a plunger '75having a piston portion 76 and an elongated stem 77 extending rearwardlythrough the rear end of the barrel and through the slots 64, 65. Thestem 77 is adapted to pass through the slots 64 and 65, whereby thesyringe may be axially aligned with the tubular portion 35 of the valvehousing and the axis of the conical portion 63 of said member 56. Byproperly manipulating the handle 62, the member 56 may be slidably movedinto contact with the collar 73 and then fixed in the position forrigidly holding the barrel 69 against movement. To remove the syringe,the handle is turned for loosening washer 60, the member 56 slidablymoved rearwardly and the barrel '70 retracted until the tip '72 isextracted from tube 35. The stem '77 may then be moved out of slots 64,65.

It will now be seen that with the valve 33 in the position shown in Fig.3, movement of the plunger '75 forwardly will expel any liquid withinthe barrel through the passage 45 and through the outlet tube 50. Withthe parts however in the position shown in Fig. '7, retraction of theplunger will cause a suction for drawing liquid through the inlet tube51 and passage 44 into the barrel. The free end of the tube 51 may beplaced within any suitable supply of liquid.

For pumping sinal quantities of liquid from said supply at regularintervals, means is provided for alternately reciprocating the plungerand oscillating the valve 42 so that with the valve in one position, theplunger may be re tracted for drawing liquid from the supply into thebarrel, and thereafter upon oscillating the valve, communication betweenthe supply and the barrel is cut off, and communication establishedbetween the barrel and the outlet pipe and upon thereafter causingforward movement of the plunger the liquid in the barrel is expelled.

, To this end there is mounted within the box 11, and on the bottom wall12 of said box, an electric motor 80 adapted to be supplied with currentby means of wires 81 connected to a plug 82 mounted on the rear wall 19,to which a socket 83 connected to any suitable supply of current may bedetachably attached. Any suitable switch 84 may be interposed in thewires 81, for controlling the motor 86. The latter may be provided witha central horizontal shaft 85 having a worm 86 thereon, said wormmeshing with a worm wheel 87 carried on a shaft 88, having a worm 89thereon. The worm 89 i adapted to mesh with a worm wheel 99 carried on avertical shaft 91.

Attached to the upper end of the shaft 91 is a cylindrical clutch member92 having a plurality of similar peripheral notches or cut away portions93. Supported by said member 92 is a second clutch member 94 having aflat annular disc portion 940. and a downwardly extending cylindricalskirt portion 95 rotatably receiving said portion 92. To the lower endof said portion 95 there is attached an annular ring 96 contacting theunderside of said member 92.

Disposed within each notch 93 and between the skirt portion 95 and saidmember 92 is a roller 97. The notches 93 are similar and each is shapedto provide an inclined surface 98 and a radial surface 99. Each of saidsurfaces 99 is provided with a socket 100 housing a small coilcompression spring 191 adapted to press the roller 97 between thesurface 99 and the inner surface of said skirted portion 95.

Thus, when the motor is running, the clutch member 92 will be rotated ina clockwise direction looking at Fig. 10. During operation of the motor,the rollers 97 will be wedged between the clutch portions 92 and 95 sothat the clutch member 94 will be rotated by said motor. The clutchmember 94 however, may be rotated in a clockwise direction, withoutrotating shaft 91 or turning the motor. During such rotation of theclutch member 94, the rollers 97 will be moved against the surface 99 torelease the clutch member 92 from the cylindrical clutch portion 95.

Attached to the underside of the disc 94a is an eccentrically disposedflat circular member or disc 103. Disposed about said disc 103 is a ring104 having an arm 105 extending radially therefrom. The ring 104 isretained in contact with the underside of the disc 940. by means ofwashers 106 attached to the underside of the circular member 103 andunderlapping said ring. The arm 105 extends toward the front of the box,and fixed to the free end of said arm is an upstanding pin 107. For thepurpose hereinafter appearing, there is rotatably mounted at theunderside of the top wall 13, a rotary disc 109 supported by a screw 110screwed to the underside of said top wall and having a head contactingthe underside of said disc. The pin 107 is pivoted to said disc 109 at apoint spaced from the center thereof, so that upon operating the motorto rotate the disc 94a, the disc 109 or will be oscillated by action ofthe eccentric ring 104 and crank arm 105.

Said disc 109 is formed at the edge thereof with an inwardly curvednotch 112; and attached to the underside of said disc is a ramal lug 113extending beyond said notch and having a vertical pin 114, extendingupwardly and disposed somewhat beyond the periphery of said disc 109.Fixed to the underside of said top wall 13 and beneath the valve 42 is abracket 115 having a portion 116 spaced from and parallel to theunderside of said top wall. Said top wall is formed for the purposehereinafter appearing, with an opening 117 coaxial with sm'd valve 42and the portion 116 of the bracket 115 is formed with an opening 118aligned with said opening 117. Rotatably mounted between the undersideof said top wall 13 and said portion 116 of the said bracket, is aGeneva gear member 110 having a downwardly extending pin i 120 journaledin said opening 118. Fixed to said curvature of the periphery of thedisc 109 on opposite sides of said slot 128.

It will be now be understood that as the motor operates and the disc 109is oscillated first in one direction, the pin 114 will engage within theslot 128, the slotted portion of said gear entering notch 112 duringthis action. When the disc 109 is oscillated in the opposite direction,the pin 114 again enters the slot 128 and rotates the Geneva gear 119 inthe opposite dim rection, so that said gear is oscillated; and due tothe engagement of the slotted pin 121 with the transverse pin 124, thevalve 42 is likewise oscillated. The parts are so proportioned thatoscillation of the valve 42 will be limited by the pin 47 and thesegmental notch 46 to bring the valve in the positions shown in Fig. 3and Fig. 7 for the purpose above described.

For the purpose of reciprocating said plunger 75, the top wall 13 isformed adjacent a side edge thereof and substantially midway between theends thereof, with a circular opening 130 receiving the shank 131 of ablock disposed beneath said top wall. Said shank is formed with a screwthreaded opening receiving the shank 132 of a screw 133 having anenlarged head contacting the upper surface of said top wall for pivotingsaid block to said top wall. An elongated curved segmental plate 134 isfixed adjacent one end thereof, to the underside of said block 135, saidplate being parallel to said top wall and extending toward the oppositeside edge thereof. Attached to the said plate at substantially themid-portion thereof, is a lug 136 extending forwardly therefrom, andinterconnecting said lug with the disc 94a, as at 137 and 138, is a link139 whereby said plate 134 may be oscillated about one end thereof whenthe disc 94a is turned. Slidably mounted on said plate 134 is a member142 having portions engaging the edges of said plate, and an upstandingpin 143. The plate 134 is provided with an upstanding wall 144 at thefree end. thereof, and rotatably and nonslidably mounted on and betweenthe block 135 and said wall 144, is an elongated screw 145 having asquare shaped end or nut portion 146 extending beyond said block 135. Amember 148 having a screw threaded opening 149 receiving the screw 145therethrough, is provided with a pair of bifurcated arms 150 forming aslot slidably receiving said pin 143. Said member 1481s prevented fromrotation by contacting a portion of the member 142.

It will now be noted that upon engaging the portion 146 of the screwwith a suitable wrench and turning said screw, the member 148 will becaused to slidably move along the screw, and due to the engagement ofthe former with the pin 143, the member 142 will be caused to slidealong the curved plate 134. Pivotally attached to the underside of saidmember 142 is a link 153 extending rearwardly therefrom, and attached tothe free end 154 of said link is a pin 155 extending upwardly therefrom.

For the purpose hereinafter appearing, the guide member 54 is formedwith an elongated slot 155a, and the top wall 13 is formed with anelongated slot 156 registering with said slot 155a. Slidably mounted onsaid guide member is a member 157 to which there is attached a screw 158having socketed portion 159 extending downwardly through said slots155a, 156, and pivotally receiving the upper end of the pin 155. It willnow be understood that as the plate 134 is oscillated, the member 157due to the connection thereof with the link 153, will be reciprocated onthe guide member 54. It will be further understood that the stroke ofthe member 157 may be adjusted by means or" the screw 145. Thus uponturning the screw to bring the plate 142 closer to the outer end 144 ofthe plate 134, the stroke will be increased. Upon turning the screw 145to bring the member 142 closer to the pivoted end of said plate 134, thestroke of said member 157 will be decreased. The curvature of the plate134 is obtained by describing an arc with the pin 155 as a center. Withsuch construction, the pin 155 will be brought back to the same pointduring each oscillation of plate 134, no matter to what position themember 142 may be moved tubular portion 164. The tubular portion 164 isadapted to slidably receive the stem 77 of the plunger 75, and a setscrew 165 at one end of said tubular portion is adapted to attach saidstem to said tubular portion. It will now be understood that the plungermay be reciprocated due to the attachment thereof to the member 157which may be reciprocated by the link 153.

The operation of the device will now be described. With the valvehousing 32 and the valve 42 mounted on the member 25, the stem '77 ofthe plunger may be first inserted within the tubular portion 164 of themember 157 and then swung about the pin 161 to bring the stem throughthe slots 64 and 65 of the members 58 and S3. The barrel 69 is thenmoved to bring the tip 72 within the tubular portion 35, and the member56 may then be slidably moved forwardly until the flaring portion 63contacts the rear 001- lar '73. The handle 62 may then be manipulated tofix the member 56 on the guide member 54. The plunger '15 may then bepushed to bring the piston 76 against the tip 72. The disc 94a may thenbe turned by hand to the position shown in Fig. 4. In such position, thecurved plate 134 is at the forward limit of its angular movement, andthe pin 155 is in the most forwardly position thereof. The disc 94apreferably extends somewhat beyond a side edge of the top wall 13 topermit hand manipulation of said wheel, and a mark 170 may be placed onthe wheel with the numeral 1 adjacent said mark to indicate the positionof the disc when the plunger is in the full forward position thereof.The screw 165 may then be tightened for fixing the stem 77 to thetubular portion 164. The disc may then be rotated by hand for causingpivotal movement of the plate 134 rearwardly to move the member 157rearwardly. The disc 94a is so rotated until the rearward limit ofangular travel of the plate 134 is reached. The disc may be formed witha mark 171 and with a number 2 adjacent said mark to indicate saidrearward limit of angular movement of said plate 134. During the lattermovement, the plunger will have been moved with the member 157 away fromthe tip '72 of the syringe. The screw 145 may then be turned by use of asuitable wrench engaging the: nut portion 146 to bring the piston to anydesired position. For example if it is desired to pump or dispense .5 c.c.

- of liquid at regular intervals, the screw is turned to bring the outerend of the plunger to the mark .5 c. 0. indicated on the tubular portionof the barrel, said barrel being suitably graduated for this purpose.

It will be noted that the member 157 moves forwardly or rearwardlyduring the turning movement of the screw 145 to bring the piston to theproper position. The motor may thereafter be started for operating themachine and the proper amount of liquid to which the syringe has beenset will be dispensed for each reciprocation of the piston.

The valve 42 is oscillated at the ends of the strokes of the piston.Thus, adjacent the end of the expelling stroke of the plunger with theparts as shown in Figs. 3 and 4, the disc 109 will cause oscillation ofthe valve 42 to change the position thereof so that when the intakestroke of the piston starts the valve will be in the position shown inFig. '7. It will be noted that a line from the pivotal point 138 to thecenter of the disc 94a is at right angles to a line from the center ofsaid disc 94a. to the center of the disc 103 so that when there is leastmovement of the piston, there is greatest movement of the disc 109. Inother words, when the plunger and the curved plate 134 to which it isconnected, are at the ends of the strokes thereof, the disc 109 is atthe mid-point of its oscillation.

It will be noted that the wrench 180 which receives the nut 146 forrotating the screw 145 may be mounted on a suitable pin fixed to the endwall 19 so as to be handy when necessary for use. A pointer 181 may befixed to a side edge of the top wall 13 to permit the marks 170 and 171to be read. The front wall 23 is provided with cut out portion oropening 182 to permit the extending edge of the disc 94a to passtherethrough. Said side wall 23 may be reinovably attached to the postsby means of thumb screws 183 to give access to the interior of the box.The other perforated side wall 22 is likewise provided with a cut outportion or opening 184 to permit the nut portion 146 of the screw 145,and the adjacent end of the plate 134 to extend therethrough.

It will thus be seen that there is provided a device in which theseveral objects of this invention are achieved and which is well adaptedto meet the conditions of practical use.

As various possible embodiments might be made of the above invention,and as various changes might be made in the embodiment above set forth,it is to be understood that all matter herein set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

1. A machine of the character described, comprising in combination, anelectric motor, pump means including a piston, actuated by said motorfor dispensing equal quantities of liquid at regular intervals, andmeans for adjusting said quantities of liquid, said last means includingmeans for changing one end point only of the stroke of said piston.

2. In combination, a barrel, a plunger therein, an inlet conduit and anoutlet conduit, a valve having passages adapted to selectively connectthe inlet and the outlet conduits with the interior of said barrel, andmeans for alternately reciprocating said plunger and rotating saidvalve, and means for adjusting the length of the stroke of said plungerwithout changing one of the end points of the stroke of said piston.

3. In a machine of the character described, a base plate, a tubularvalve housing mounted thereon, a valve rotatably mounted within saidhousing, said housing being provided with three passages communicatingwith the interior thereof, said valve having a pair of openings thereinadapted to selectively connect one of said passages with each of theother of said passages respectively, a pumping device connected to thefirst of said passages including a barrel and plunger, and means foractuating said plunger and rotating said valve at the end only of eachstroke of said plunger.

4. In combination with an inlet and an outlet pipe, means for drawingliquid through said inlet pipe and expelling the same through saidoutlet pipe periodically in equal amounts, said means comprising a valveand a pump and means for alternately actuating said pump and said valve,said pump comprising a motor, a piston operatively connected to saidmotor and adapted to be reciprocated thereby. and means for adjustingthe length of stroke of said piston without changing one end point ofthe stroke of said piston.

5. In combination with a rotary valve and a pumping means including areciprocating member, means for rotating said valve and reciprocatingsaid member, said means comprising a member rotatable with said valve, asecond member adapted to engage said reciprocating memher, and meansassociated with said second member for rotating said rotary member, saidmeans comprising a rotatable plate, an electric motor and a one-wayclutch connecting said motor and said rotatable plate.

6. A pipette machine comprising a basa'a valve housing fixed thereto,said housing having an outlet passage and an inlet passage, and a thirdpassage communicating with the interior thereof, a rotary valve mountedwithin said housing having at pair of passages adapted to selectivelyconnect said third passage with said inlet passage and outlet passage, asyringe comprising, a graduated barrel having an opening communicatingwith said third passage, a plunger within said barrel and means forreciprocating said plunger and oscillating said valve, and means foradjusting the length of the stroke or" said plunger, said meanspermitting the plunger to be moved to a predetermined point in thebarrel during reciprocation irrespective of said adjustment.

'7. A pipette machine comprising a base, a valve housing fixed thereto,said housing having an outlet passage and an inlet passage, and a thirdpassage communicating with the interior thereof, a rotary valve mountedwithin said housing having a pair of passages adapted to selectivelyconnect said third passage with said inlet passage and outlet passage, abarrel having an opening communicating with said third passage, aplunger within said barrel and means for reciprocating said plunger andoscillating said valve, said means comprising an electric motor, a discto be rotated by said motor, a second disc rotatably mounted on saidbase, eccentric means interconmeeting said discs for oscillating saidsecond disc, means cooperating with said second disc and valve foroscillating the latter, a member pivotally mounted on said base, a linkinterconnecting said pivoted member with said first disc for oscillatingsaid pivoted member during rotation of said first disc, a memberslidably mounted on said base and fixed to said plunger, and a linkinterconnecting said slidably mounted member with said pivoted member.

8. A pipette machine comprising a box having a bottom wall and a topwall, a syringe comprising a barrel mounted on said top wall, and aplunger slidably mounted in said barrel, a member having an inletpassage and an outlet passage, a valve having means for selectivelyinterconnecting the outlet end of said barrel with said inlet passageand outlet passage, and means for reciprocating said plunger andoscillating said valve, said means comprising an electric motor mountedon said bottom wall, a vertical shaft connected by reduction gearing tosaid motor shaft. a member having a clutch connection to said shaftadapted to be rotated by said shaft in one direction, means operativelyinterconnecting said member and said valve for oscillating the latter asmember is rotated by said motor, and means interconnecting said memberwith said plunger for reciprocating the latter as said member isrotated.

9. In a machine of the character described, a support, a syringecomprising a barrel mounted on said support, a plunger within saidbarrel, and means for reciprocating said plunger, comprising a rotarymember, a member pivoted directly to said support,a link interconnectingsaid rotary member said pivoted member for osc'illating the latter assaid rotary member is rotated, a member slidably .iounted on saidpivoted member, and a link interconnecting said slidably mounted memberwith said plunger.

10. In a machine of the character described, a support, a syringecomprising a barrel mounted on said support, a plunger within saidbarrel, and means for reciprocating said plunger, comprising a rotarymember, a member pivoted directly to said support, a linkinterconnecting said rotary member and said pivoted member foroscillating the latter as said rotary member is rotated, a memberslidably mounted on said pivoted memher, a link interconnecting saidslidably mounted member with said plunger, and means for causing slidingmovement of said slidably mounted member f or changing the stroke ofsaid plunger.

11. In a machine of the character described, a support, a syringecomprising a barrel mounted on said support, a plunger within saidbarrel, and means for reciprocating said plunger, comprising a rotarymember, a member pivoted to said support, a link interconnecting saidrotary member and pivoted member for oscillating the latter as saidrotary member is rotated, a member slidably mounted on said pivotedmember, a link interconnecting said slidably mounted member with saidplunger, and means for causing sliding movement of said slidably mountedmember for changing the stroke of said plunger, said pivoted memberhaving the curvature of an arc described with a radius having the lengthof said last link, whereby said plunger may be moved to a predeterminedposition at the end of one of its strokes in all adjusted positions orsaid slidably mounted member. 12. A pipette machine comprising aportable box having a bottom wall and a top Wall, a syringe comprising abarrel, mounted on said top wall, and a plunger mounted therein, a valvehousing mounted on said top wall having an outlet passage and an inletpassage, and a third passage communicating with the outlet end of saidbarrel, a rotary valve mounted within said valve housing having apassage adapted to connect said inlet passage with the outlet end ofsaid barrel in one position of said valve, and a second passage forconnecting said outlet passage with the outlet end of said barrel inanother position of said valve, and means for reciprocating said plungerand rotating said valve, said meanscomprising an electric motor mountedwithin said box on said bottom wall, a vertical shaft rotatablysupported by said motor, reduction gearing interconnecting the motorshaft with said vertical shaft, a rotary ember having a clutchconnection to said Vertical shaft, a member rotatably mounted on saidtop wall, crank means interconnecting said rotary member udth saidrotatably mounted member for oscillating the latter as said rotarymember is rotated, a member mounted on said top wall for rotation withsaid valve, havinga Geneva gear connection to said rotatably mountedmember, a member pivoted to said top wall, a link interconnecting saidrotary member with said pivoted member, a member slid-ably mounted onsaid pivoted member, a second member slidably mounted on said top walland connected to said plunger, and a link interconnecting said firstslidably mounted member with said second slidably mounted member and asecond passage for connecting said outlet passage with the outlet end ofsaid barrel in another position of said valve, and means forreciprocating said plunger and rotating said valve, said meanscomprising an electric motor mounted within said box on said bottomwall, a vertical shaft rotatably supported by said motor, reductiongearing interconnecting the motor shaft with said vertical shaft, arotary member having a clutch connection to said vertical shaft, amember rotatably mounted on said top Wall, crank means interconnectingsaid rotary member with said rotatably mounted member for oscillatingthe latter as said rotary member is rotated, a member mounted on saidtop wall for rotation with said valve, having a Geneva gear connectionto said rotatably mounted member, a member pivoted to said top wall, alink interconnecting said rotary member with said pivoted member, amember slidably mounted on said pivoted member, a second member slidablymounted on said top wall connected to said plunger, a linkinterconnecting said first slidably mounted member with said secondslidably mounted member, and means for causing sliding movement of saidfirst slidably mounted member along said pivoted member.

14. A pipette machine comprising a portable box having a bottom wall anda top wall, a syringe comprising a barrel, mounted on said top wall, anda plunger mounted therein, a valve housing mounted on said top wallhaving an outlet passage and an inlet passage, and a third passagecommunicating with the outlet end of said barrel, a rotary valve mountedwithin said valve housing, having a passage adapted to connect saidinlet passage with the outlet end of said barrel in one position of saidvalve, and a second passage for connecting said outlet passage with theoutlet 1 end of said barrel in another position of said so necting themotor shaft with said vertical shaft,

a rotary member having a clutch connection to said vertical shaft, amember rotatably mounted on said top wall, crank means interconnectingsaid rotary member with said rotatably mounted member for oscillatingthe latter as said rotary member is rotated, a member mounted on saidtop Wall for rotation with said valve having a Geneva gear connection tosaid rotatably mounted member, a member pivoted to said top wall, a linkinterconnecting said rotary member with said pivoted member, a memberslidably mounted on said pivoted member, a second member slidablymounted on said top wall connected to said plunger, a linkinterconnecting said first slidably with said second slidably mountedmember, and means for causing sliding movement of said first slidablymounted member along said pivoted member, said pivoted member beingcurved and the curvature of an arc described by a radius equal to thelength of said second link.

15. In a machine of the character described, a support, a tubular memberfixed thereto, a tubular valve housing attached to said tubular member,said valve housing havin a tapering bore and a pair of tubular portionsextending from one side thereof ,and a third tubular portion extend ingfrom another side thereof, a rotary tapering valve rotatably mountedwithin said valve housing, and having a pair of passages adapted toselectively connect said third tubular portion with each of said pair oftubular portions, a member slidably mounted on said support having aconical portion formed with a radial slot, a syringe comprising a barrelhaving the forward end thereof connected to said third tubular portion,and the rear end thereof engaging said conical portion, and a plungerslidably mounted within said barrel and having a stem extending throughsaid slot, a second member slidably mounted on said support, a memberpivoted to said second slidably mounted member and having a tubularportion receiving said stem therethrough.

16. In a machine of the character described, a base, a tubular memberfixed thereto, a tubular valve housing having a portion slidablyreceived within said tubular member, means for fixing said member tosaid tubular member, said housing having a pair of tubular portionsextending in one direction, and a tubular portion extending in anotherdirection, a tapered rotary valve mounted within said tubular housinghaving a pair of passages adapted to selectively interconnect said thirdtubular portion with each of said pair of tubular portions, said rotaryvalve having a flange formed with a segmental notch, a pin fixed to saidvalve housing extending into said notch for limiting rotary movement ofsaid valve, and means for causing rotation of said rotary valve, saidmeans comprising a member rotatably mounted on said support, means foroscillating said member, said valve being formed v ith a socket and apin traversing said socket, and a pin fixed to said member extendinginto said socket, and provided with a slot receiving said first pintherethrough.

17. In a machine of the character described, a base, a tubular memberfixed thereto, a tubular valve housing having a portion slidablyreceived within said tubular member, means for fixing said member tosaid tubular member, said housing having a pair of tubular portionsextending in one direction, and a tubular portion extending in theopposite direction, a tapered rotary valve mounted within said tubularhousing having a pair of passages adapted to selectively interconnectsaid third tubular portion with each of said pair of tubular portions,said rotary valve having a flange formed with a segmental notch, a pinfixed to said valve housing extending into said notch for limitingrotary movement of said valve, and means for causing rotation of saidrotary valve, said means comprising a member rotatably mounted on saidsupport, means for oscillating said member, said valve being formed witha socket and a pin traversing said socket, and a pin fixed to saidmember extending into said socket, and provided with a slot receivingsaid first pin therethrough, said rotary valve being formed with anannular groove, and a curved member pivoted to one end of said tubularhousing adapted to be moved into said groove for preventing axialmovement of said rotary valve with respect to said valve housing.

18. In a pipette machine, a syringe comprising a graduated barrel and aplunger slidably mounted therein, a valve housing having an outletpassage and an inlet passage and a third passage communicating with theoutlet end of said barrel, a rotary valve within said housing having apassage adapted to connect said inlet passage with the outlet end ofsaid barrel in one position of said barrel, and a second passage forconnecting said outlet passage with the outlet end of said barrel inanother position of said valve, and means for reciprocating said plungerand third passage, a member slidably mounted on said base and adapted toengage the rear end of said barrel, a plunger slidably mounted withinsaid barrel and projecting from the rear end of the latter, a rotaryvalve mounted within said valve housing and having passages adapted toselectively connect said third passage with said inlet and outletpassages, a member slidably mounted on said base and attached to saidplunger and means for reciprocating said last mentioned slidacle memberand oscillating said valve.

EDWIN C. WEISKOPF.

